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<p>Zinc sulfide (ZnS) nanoparticles (NPs) were synthesized via a controlled chemical precipitation method and calcined at 150, 250, and 350&#xa0;°C to optimize their structural and catalytic properties for piezocatalytic Cr(VI) reduction. X-ray diffraction confirmed phase-pure cubic ZnS with enhanced crystallinity and particle size at higher calcination temperatures, while SEM–EDX verified uniform Zn–S distribution and morphology changes. Under optimized conditions (pH 5–7, 250 rpm, 60 min), the sample calcined at 150&#xa0;°C achieved the highest Cr(VI) reduction efficiency of 90.0%, compared to 66.8 and 20.0% for the 250 and 350&#xa0;°C samples. Kinetic analysis indicated that the reduction process followed a pseudo-second order model (R<sup>2</sup> = 0.961–0.978), suggesting chemisorption as the rate-limiting step. Thermodynamic parameters confirmed an endothermic and spontaneous reaction, with ΔH values of 41.19–74.30 kJ mol<sup>−1</sup>, ΔS values of 0.151–0.266 kJ mol<sup>−1</sup> K<sup>−1</sup>, and negative ΔG values. Response surface methodology identified reaction time as the most significant factor influencing reduction efficiency. The ZnS NPs retained over 78% of their activity after four reuse cycles, demonstrating excellent stability and reusability. These results highlight the potential of low-temperature–calcined ZnS NPs as efficient, stable, and energy-saving piezocatalysts for Cr(VI) remediation.</p>

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Mechanically induced water remediation: investigating the kinetic and thermodynamic pathways for optimizing Cr(VI) reduction using ZnS nano-piezo catalyst

  • 期刊论文

  • 发表日期：

    2025年9月16日

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  • Karukh Ali Babakr,
  • Ibrahim Nazem Qader,
  • Omed Amiri,
  • Pshdar Ahmed Ibrahim,
  • Peshawa H. Mahmood,
  • Ibrahim Luqman Salih,
  • Dlshad Aziz Hamid,
  • Safar Saeed Mohammed,
  • Hazhar Hamad Rasul,
  • Abubakr Wsu Muhammed

摘要

Zinc sulfide (ZnS) nanoparticles (NPs) were synthesized via a controlled chemical precipitation method and calcined at 150, 250, and 350 °C to optimize their structural and catalytic properties for piezocatalytic Cr(VI) reduction. X-ray diffraction confirmed phase-pure cubic ZnS with enhanced crystallinity and particle size at higher calcination temperatures, while SEM–EDX verified uniform Zn–S distribution and morphology changes. Under optimized conditions (pH 5–7, 250 rpm, 60 min), the sample calcined at 150 °C achieved the highest Cr(VI) reduction efficiency of 90.0%, compared to 66.8 and 20.0% for the 250 and 350 °C samples. Kinetic analysis indicated that the reduction process followed a pseudo-second order model (R2 = 0.961–0.978), suggesting chemisorption as the rate-limiting step. Thermodynamic parameters confirmed an endothermic and spontaneous reaction, with ΔH values of 41.19–74.30 kJ mol−1, ΔS values of 0.151–0.266 kJ mol−1 K−1, and negative ΔG values. Response surface methodology identified reaction time as the most significant factor influencing reduction efficiency. The ZnS NPs retained over 78% of their activity after four reuse cycles, demonstrating excellent stability and reusability. These results highlight the potential of low-temperature–calcined ZnS NPs as efficient, stable, and energy-saving piezocatalysts for Cr(VI) remediation.